Principle classification
Thickness gauges can be roughly divided into:
1, contact thickness gauge
Contact area size division:
Point contact thickness gauge
Thickness gauge
2, non-contact thickness gauge
Non-contact thickness gauges can be divided into the following according to their different test principles:
Laser thickness gauge
Ultrasonic thickness gauge
Coating Thickness Gauge
X-ray thickness gauge
White light interference thickness gauge
Electrolytic thickness gauge
Tube thickness gauge
How to choose
1. Copper and chrome layer on plastic: It is recommended to use Coulometric thickness gauge (which will damage the coating) or X-ray thickness gauge (non-destructive measurement). For example, the copper layer can be considered eddy current thickness gauge at 10m~200m. measuring).
2, galvanized layer on the metal parts: If the steel substrate should be used economical magnetic induction method thickness gauge (non-destructive measurement). Other metal substrates are coulometric thickness gauges (which can damage the coating) or X-ray thickness gauges (non-destructive measurements).
3, the electrophoretic paint on the iron substrate, the paint should use the economical magnetic induction method thickness gauge (non-destructive measurement). For electrophoretic paints on other metal substrates, the paint should use an economical eddy current thickness gauge (non-destructive measurement).
4. Dry film refers to a paint coating that has been cured.
5, chrome layer reference 2 items, 1 item.
6, the interior and exterior parts of the paint can only be used by the cutting method (PIG, will destroy the coating), ultrasonic method (non-destructive measurement) can measure more than 10 microns coating, but sometimes not measured.
7. Price: magnetic induction method, eddy current method 0.6~30,000, coulometric method 0.8~60,000; ultrasonic method 5.5~60,000; X-ray thickness gauge 25~400,000.
Precautions
The testing methods of the thickness gauge are mainly: magnetic thickness measurement method, radiation thickness measurement method, electrolytic thickness measurement method, eddy current thickness measurement method, and ultrasonic thickness measurement method.
Measurement considerations:
1. When carrying out the test, it should be noted that the metal magnetic and surface roughness of the standard piece collective should be similar to the test piece.
2. When measuring, the side head is perpendicular to the surface of the sample.
3. Pay attention to the critical thickness of the base metal when measuring. If it is larger than this thickness, it will not be affected by the thickness of the base metal.
4. Pay attention to the influence of the curvature of the test piece on the measurement. Therefore, it is not reliable when measuring on the surface of a curved test piece.
5. Before measuring, please pay attention to whether other electrical equipment around will generate magnetic field, if it will interfere with the magnetic thickness measurement method.
6. When measuring, be careful not to measure at the inner corner and near the edge of the test piece, because the sudden change of the surface shape of the general thickness gauge specimen is very sensitive.
7. Keep the pressure constant during the measurement, otherwise it will affect the measured reading.
8. When testing, pay attention to the direct contact between the instrument probe and the tested component, so the ultrasonic thickness gauge removes the attached material from the opposite side.
Application of different types of thickness gauges
1. The laser thickness gauge is a non-contact dynamic measuring instrument that uses the reflection principle of the laser to measure the thickness of the product according to the photo-cutting method and observes the micro-geometry of the machined surface of the machine. It directly outputs digital signals to industrial computers and processes data quickly and outputs bias values ​​to a variety of industrial equipment.
2. X-ray thickness gauge is a non-contact dynamic measuring instrument when the X-ray penetrates the material to be tested, the intensity of the X-ray changes and the thickness of the material. . It takes PLC and industrial computer as the core, collects the calculated data and outputs the target deviation value to the rolling mill thickness control system to achieve the required rolling thickness. Main application industries: strip and foil processing of non-ferrous metals, strip processing of metallurgical industry.
3, paper thickness gauge: for the measurement of the thickness of various films, paper, cardboard and other sheet materials below 4mm.
4, film thickness gauge: used to determine the thickness of films, sheets and other materials, wide measurement range, high measurement accuracy, with data output, arbitrary position zero, metric conversion, automatic power off and so on.
5. Coating thickness gauge: used to measure the thickness of the coating on iron and non-ferrous metal substrates.
6. Ultrasonic Thickness Gauge: Ultrasonic Thickness Gauge is used for thickness measurement according to the principle of ultrasonic pulse reflection. When the ultrasonic pulse emitted by the probe passes through the measured object to reach the material interface, the pulse is reflected back to the probe, and the ultrasonic wave is accurately measured. The time of propagation in the material determines the thickness of the material being tested. Various materials that enable ultrasonic waves to propagate inside at a constant speed can be measured using this principle.
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